Book authors are always looking for ways to promote their books, often without spending any money to do so. Why, then, are so many book authors missing out on free online book marketing opportunities?

Here are four missed book marketing opportunities, and what you can do to avoid missing them:

Missed opportunity #1:

A book on blogging is out, and several other books on blogging are recommended in the resources section. One of the authors whose book is recommended accidentally finds out about this new book because no one, neither the publisher nor the publisher’s publicity department, nor the author or the author’s publicist, has notified the authors of the recommended books.

For the publisher and author of the blogging book, this is like leaving money on the table. It should have been someone’s marketing responsibility to contact every author whose book is recommended. The contact email should 1) inform the author that her book is recommended and 2) suggest that the author consider publishing, linking to, or recommending the new blogging book.

And why would recommended authors say yes to this email request? Because having your blogging book recommended in someone else’s book on blogging is a pretty big seal of approval. By going out of their way to help promote this new book, the other authors get the benefit of giving their own books a thumbs up.

Missed opportunity #2:

A blogger posts a review of his book on his blog, and comments are enabled on the blog. Your Google Alerts pick up the review even if the blogger hasn’t notified you about the review. You go to the blog, read the review, and then you leave.

This review is free marketing to you. Increase the marketing value by leaving a comment thanking the blogger for reviewing your book. And say something in the comment that shows you appreciate this specific review. (Even if the review isn’t great, try to find something positive to say about your book’s chance of getting featured on the blog.)

And come back the next day to see if there were any other comments. Then add a second comment thanking the people who have left comments by name. Refer to something that each one said. Here’s an example of what you can leave in a single comment:

Sally, I’m glad you liked the way the protagonist got out of her big dilemma. It took me several weeks to find that solution.

John, I see that places are important to you as a background for a book. I went to San Francisco to check that I had my setup correct.

Marlene, thank you for passing my book on to your sister. I hope she likes it as much as you do.

With these comments, you 1) revealed interesting facts about yourself (for example, you took weeks to solve a story question) and 2) encouraged potential readers to start a relationship with you. Acknowledging these potential readers as individuals means they’re much more likely to start following what you’re doing.

Missed opportunity #3:

Someone tweets that they enjoyed your book and provides the link to your website from where the book can be purchased. You tweet “I’m glad you enjoyed my book” and don’t include the link.

It is perfectly acceptable to include your own link in this case. In fact, you are doing your followers a favor. If they didn’t see the original tweet and didn’t know about your book, they might be upset that you didn’t provide the information (the link) in your reply tweet. By providing the link, you have made it easy for your followers to view your book if they want to. (And if they don’t want to, that’s fine. They just don’t click the link.)

Missed opportunity #4:

The home page of your website displays a large photo of your book cover with no content information to “hook” potential readers. Here’s an example: A website advertised a new book with a title that included the last name of a racehorse owner and made no mention of racehorses. Only by clicking through to the site did it become apparent that the guy in the title had to do with a huge horse racing scandal.

Now, even though a potential reader might not recognize the guy’s name in the book’s title, if there was a headline and brief information that this book tells the true inside story of the biggest horse racing scandal of the century (the “hook” ), the potential reader might be interested in buying the book even if they didn’t recognize the boy’s name. (Who isn’t interested in reading about large-scale scandals? It’s human nature.)

When planning a book author’s website, it’s important to consider what elements the potential reader needs to see immediately and easily to consider buying the book. This is usually clear information about what the story is about and what the “hook” is. (As well as having a big BUY THIS BOOK button next to the book cover image.)

In conclusion, book authors should be on the lookout for every legitimate promotional opportunity that comes their way. And one of the best ways to get a book promoted is to publicly thank the people who have promoted your book. That’s just good manners.